And the most bedbug-infested U.S. city is …

The exact cause is not known, but experts associate the resurgence with increased resistance of bed bugs to available pesticides, greater international and domestic travel, lack of knowledge regarding control of bed bugs due to their prolonged absence, and the continuing decline or elimination of effective pest control programs at state and local public health agencies.

The only people that are happy, it would seem, are pest control specialists. To that end, Orkin has announced its top 50 bed bug cities for 2012. The company says there has been a nearly 33 percent increase in bed bug business compared to 2011.

The following cities are ranked in order of the number of bed bug treatments Orkin performed from January to December 2012 along with their shift, if any, in ranking compared to January to December 2011.

Cities ranked in order of bed bug treatments Orkin performed from Jan.-Dec. 2012. (Orkin)

In a news release from the company, Orkin entomologist Ron Harrison said, “This list shows that bed bugs continue to be a problem throughout the U.S. Based on the diversity of cities on the list, we all need to be very cautious when we travel—whether it is business or pleasure, or to visit family, friends or vacation. We need to be vigilant wherever we are and take the proper precautions.”

Those wishing to take precautions are in luck.

The Bedbug Registry offers travelers a repository of hotel locations where bed bugs have been sighted. It should be noted, with extreme caution, that these are user generated reports and have in no way been verified.

Houston area bed bug reports. (The Bedbug Registry)

Despite the fact that Houston has fallen out of Orkin’s dirty dozen in terms of bedbug activity, the registry (see local map above) has a healthy list of Houston hotspots.